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according to his own measures of probability, and trusting to future researches to reveal to us the ancient history of the earth we tread, we shall confine ourselves to a few considerations relative to the manner in which the rocks we have undertaken to treat of were deposited. We find them mostly formed of thin strata with parallel surfaces, regularly deposited one over the other, and consisting alternately of strata of limestone, clay, and sandstone, thus proving the habitual tranquillity of the water beneath which they were deposited. On the other hand, the large rolled granite rocks testify that occasionally these same waters were violently agitated. Lastly, the great number of strata, the ends of which are visible in some places, assure us that the formation of the fucoidal rocks must have occupied a long period. Gypsum is not so frequent or abundant in rocks of this series as in the other. Sometimes it is arranged in strata, or crystals of considerable size are scattered through the clay; again, it forms large deposits which do not exhibit any signs of stratification: in this case its structure is eminently crystalline. An example of its extraordinary arrangement may be observed a little more than two miles to the west of Melfi, at a place called Masseria del Gesso, and a very large deposit occurs in the territory of Marcerinaro, in the province of Catanzaro, extending more than a mile. Observing the conditions of these deposits, and reflecting that gypsum is not so generally diffused as the other rocks of the same formation, we are of opinion that its origin must have depended on particular causes, probably of the same nature as those which in our days, on a smaller scale, are generating gypsum in the valley of Ansanto, in the province of Avellino. The largest crystals of gypsum formed in argil, are found close to the village of S. Potito, south-east of Piedimonte di Alife. It is not scarce in Terra di Lavoro, being found distinctly stratified near Mola di Gaeta, Casanova, Torrecuso, and in some other places. In the province of Cosenza, strata may be seen in the clay on the right bank of the torrent Pantusa, between Cerisano and Marano, and near the salt pits of Altamonte. In the last region gypsum forms a part of the immense deposits of Rock salt, of which (as it is foreign to the aim of this work to treat of them more particularly) we shall only say, that in our opinion they belong to the fucoidal